RE: [wsbpel] Example for how compensation relates to WS-T (BA)

["Edwin Khodabakchian" <edwink@collaxa.com>]

Assaf,

I think that we all agree that although this might be clear in a few
people's mind, there is room for interpretation and for the sake of
interoperability the spec needs further clarification on that specific
subject. 

I am suggesting that we start by defining a simple example as a way to
identifying the areas that need further clarification within the spec.

Edwin

 

> 
> -----Original Message-----
> From: Assaf Arkin [mailto:arkin@intalio.com] 
> Sent: Friday, June 20, 2003 12:41 PM
> To: edwink@collaxa.com
> Cc: 'Satish Thatte'; 'Yuzo Fujishima'; wsbpel@lists.oasis-open.org
> 
> Suppose you have some process A that performs some operation 
> and supports compensation through its process-level 
> compensation handler. 
> (The topic of discussion is process-level compensation 
> handlers, not scope-level compensation handlers, which are 
> covered in the appendix)
> 
> You have some process B that performs an activity called X. 
> Activity X invokes process A and so process B may later on 
> decide to invoke A's compensation handler. Assume you would 
> want to use WS-TX to do that. 
> Interoperability means that two systems would understand how 
> it works and do it in the same manner (barring any other differences).
> 
> What would the compensation handler for activity X look like?
> 
> Let's say A is never compensated unless there is a 
> compensation handler for activity X. The compensation handler 
> for activity X does not need to do anything, so it contains 
> an <empty> activity. According to the current spec, if the 
> compensation handler includes an <empty> activity then 
> nothing would happen. So there needs to be a clarification 
> that some work would indeed happen and that this compensation 
> handler may actually throw a fault (if A returns 'faulted').
> 
> Another implementation may decide that to compensate A you 
> need to invoke the default compensation handler for X. So if 
> X has a compensation handler containing <empty> it would not 
> invoke A's compensation handler, but if it has no 
> compensation handler then A gets compensated using WS-TX. You 
> can use the <empty> activity to prevent A from being 
> compensated (a good thing), but you can't interact with A 
> within X's compensation handler, which violates the need to 
> pass data to a compensation handler.
> 
> Another possibility is for X's compensation handler to 
> explicitly send a compensation message to A. Unfortunately, X 
> doesn't know the participant or coordination addresses and so 
> can't pass them to A's WS-TX implementation.
> 
> Considering the lack of clarification in the specification I 
> am very curious to see what such an example would look like.
> 
> arkin
> 
> 
> Edwin Khodabakchian wrote:
> 
> >I suggest that we take one of the examples used by Satish in the F2F 
> >(travel
> >procurement) and try to get down into the details of how exception 
> >management and compensation management would be implemented. 
> This will 
> >help us flush out the details of how BPEL and WS-Transaction 
> (BA) work together.
> >
> >If we decide that this is valuable, I volunteer to implement 
> the BPEL 
> >processes once the use case has been agreed on.
> >
> >Thoughts?
> >
> >Edwin
> >  
> >
> 
> 
>